A semiconductor power conversion device includes a converter unit and an inverter unit. The converter unit of the semiconductor power conversion device includes a converter circuit that converts an alternating current to a direct current by a diode bridge to supply the direct current to the inverter unit, and a smoothing capacitor that removes ripple components from the DC voltage into which the converter circuit has converted the AC voltage. In some cases, the converter unit is provided with an inrush-current suppression circuit for suppressing flow of a high inrush current through diode elements within the diode bridge of the converter unit at the time of power-on to charge the smoothing capacitor of the converter unit and a smoothing capacitor within the inverter unit connected to the converter unit. The inrush-current suppression circuit is provided between the converter circuit and the inverter unit and includes an inrush-current suppression resistor and a contactor connected in parallel to the inrush-current suppression resistor.
An uninterruptible power supply device disclosed in Patent Literature 1 includes a rectifier, which is connected to an AC power supply to convert an input alternating current to a direct current; an inverter, which converts the direct current to an alternating current with a fixed voltage and a fixed frequency; a smoothing capacitor and a battery, which are connected to a DC intermediate circuit, which couples the DC side of the rectifier with the DC side of the inverter. The uninterruptible power supply device further includes an inrush-current suppression device. In the inrush-current suppression device described in Patent Literature 1, a current-limiting circuit configured by connecting a current-limiting resistance and a resistance short-circuit switch in parallel is inserted into the AC input side of the rectifier, a switching circuit configured by connecting a semiconductor switch element and an element short-circuit switch in parallel is inserted into the DC intermediate circuit, a first smoothing capacitor is connected between the switching circuit and the rectifier, and a second smoothing capacitor and the battery are connected between the switching circuit and the inverter.